Use this seismology calculation to reproduce a stated convention, screen observations, or compare scenarios whose units, coordinate conventions, catalog selection, and model assumptions are known.

Δ_i

Required list. Epicentral distances.

t_i

Required list. Observed travel times.

v_red (km/s)

Required number in km/s. Reducing velocity.

The cited overview of Seismology supplies background for the terminology and domain context used by this tool.^[1]

Convert absolute travel times to reduced times t − Δ/v_red for slowness plotting. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

t' (s)

Returned list in s. Reduced times.

dt/dΔ (s/km)

Returned number in s/km. Segment-averaged slowness.

• Earth structure, source geometry, path effects, site response, instrument response, catalog completeness, uncertainty, and the fitted range can dominate the accuracy of simplified seismic calculations.
• v_red must be at least 0.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

For analysis or hazard decisions, retain uncertainty and provenance and compare the result with waveform processing, calibrated regional models, and guidance from qualified seismologists or the responsible agency.

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